1. Field of the Invention
The present invention relates to a seal that has a textured patient-contacting surface to improve comfort during contact with the patient's face and a polished surface to maintain aesthetic appeal, and to a respiratory mask using such a seal.
2. Description of the Related Art
A variety of respiratory masks are known that have flexible seals and cover the nose, mouth, or both of a human patient. The seals, which are also commonly referred to as cushions, are intended to create a seal against the patient's face. Because of the sealing effect that is created, gases can be provided at a positive pressure within the mask for delivery to the airway of the patient.
The uses for such masks range from high altitude breathing, i.e., aviation applications, to mining and fire fighting applications, to various medical diagnostic and therapeutic applications. For example, such masks are used in the delivery of continuous positive airway pressure (CPAP) or variable airway pressure, such as a bi-level pressure that varies with the patient's respiratory cycle or an auto-titrating pressure that varies with the monitored condition of the patient. Typical pressure support therapies are provided to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure.
A requisite of such respiratory masks is that they provide an effective seal against the patient's face to prevent leakage of the gas being supplied, while also providing a comfortable patient/seal interface. This problem is most crucial because such masks are typically worn for an extended period of time. One concern in such a situation is that a patient may avoid wearing an uncomfortable mask, defeating the purpose of the prescribed pressure support therapy.
Examples of conventional respiratory masks used in the medical field for providing a positive airway pressure to a patient include U.S. Pat. No. 5,243,971, which teaches a bubble-type of patient interface in which the seal is attached to a shell and extends from the shell in a concave fashion. Other conventional masks are disclosed, for example, in U.S. Pat. Nos. 5,540,223 and 6,467,483. A still further type of mask is described in U.S. Pat. No. 5,647,357, which uses a gel material as the seal or cushion to maximize patient comfort and sealing properties. U.S. Pat. No. 4,971,051 teaches a mask in which the seal includes multiple flaps, again to optimize patient comfort and the sealing property.
In each of these conventional seals and others, the patient-contacting surface of the seal or the flap is very smooth, which is also referred to as being highly polished. Polished surfaces can cause skin irritation in some patients. The present inventors opined that such irritation is the result of an inability of the skin underlying the polished to “breathe”. That is moisture and/or heat may build up under the polished cushion. Polished surfaces also tend to feel sticky or tacky to the touch, causing the seal to stick to the patient's skin. This stickiness may cause the cushion to dislodge from the shell or faceplate to which the seal is mounted rather than shift on the patient if a torque or pulling force is applied on the mask